Optimization of saccharification of sweet sorghum bagasse using response surface methodology

Abstract

The lignocellulose rich sweet sorghum bagasse (SSB) is a good feedstock for bioethanol production after conversion of its insoluble carbohydrates, mainly cellulose, to fermentable sugars. Main focus of the present investigation was therefore, to determine the optimum conditions for enzymatic saccharification of SSB using indigenously produced cellulases from a novel fungal consortium of Aspergillus flavus F-80 and Aspergillus niger MTCC-2425. Response surface methodology was adopted by using a three factor-three level Box–Behnken design by selecting substrate concentration (%, w/v), saccharification time (h) and enzyme loading (FPUg−1substrate) as the main process parameters. Data obtained from RSM were subjected to the analysis of variance (ANOVA) and analyzed using a second order polynomial equation. The developed model was found to be robust and was used to optimize the % saccharification yield during enzymatic hydrolysis. Under optimized conditions (substrate concentration 6%, w/v, time 48h and enzyme loading of 22FPUg−1substrate), maximum saccharification yield of 51.21% was achieved. Structural modification of SSB due to enzymatic saccharification was supported by changes in thermal decomposition behavior and pore formation observed during thermogravimetric and SEM analysis, respectively.